Li Feng was a little stunned when he heard Dumbledore's request. He was confused. There were plenty of people at Hogwarts capable of keeping an eye on Peter Pettigrew, such as the House Heads Dumbledore trusted deeply. Every one of them had their own specialties.
Minerva McGonagall might be powerful but lacked experience in surveillance. But what about Professor Severus Snape, the man whose face was either naturally gloomy or permanently expressionless? Not only was he exceptionally capable, he had even relied on his superb acting to infiltrate Voldemort's inner circle. Having Severus Snape watch Peter would be as easy as playing around.
Could it be that Dumbledore was worried Professor Snape would learn that his beloved Lily Potter had actually been killed by Peter Pettigrew, and feared Snape might lose it and smack Peter to death? That would ruin the witness needed to clear Sirius's name. After all, Snape and Sirius did not get along, and Snape himself was skilled at brewing all kinds of Potions. It would be quite easy for him to quietly kill someone without anyone noticing.
Speaking of which, Li Feng had to give Snape's view of love a thumbs-up. Just look at the man. He had watched the woman he loved become someone else's wife and have children, especially when that "someone else" was a person he hated.
And after all these years, never mind that Snape still had not let go of Lily Potter, just having Harry Potter, who looked so much like his romantic rival, constantly wandering around him was annoying enough. Yet he still had to protect the boy for the future of the magical world.
Li Feng admired Snape's devotion, but he knew he could never do the same. If Li Feng were Snape, once Lily chose to leave him